tach_schem

1 comment to tach_schem

The reason why the circuit doesn’t work well is because the transistor is biased incorrectly. Resistor R3 is too high and doesn’t allow the transistor to turn ON. A better approach is to remove resistor R3 and connect the Arduino Analog Input to the transistor emitter. For more detail info, download the Fairchild application note @ http://www.fairchildsemi.com/an/AN/AN-3005.pdf